One vertex per element, one color per generator, with an edge from x to x·s.
(9,10)(11,16)(12,18)(13,21)(14,19)(15,20)(17,22)(23,24)(25,26)(27,33)(28,29)(30,34)(31,32)(35,38)(36,37)(39,40) involution — undirected(1,2)(3,8)(4,6)(5,7)(9,11,15,23)(10,16,20,24)(12,14,22,21)(13,18,19,17)(26,32)(28,33)(34,40)(36,38)(1,3,5,6)(2,4,7,8)(9,12)(10,17)(11,21)(13,24)(14,23)(15,22)(16,19)(18,20)(25,27,31,29)(26,33,32,28)(30,35,39,37)(34,38,40,36)(1,4,5,8)(2,3,7,6)(9,12)(10,18)(11,14)(13,24)(15,22)(16,19)(17,20)(21,23)(25,28)(26,27)(29,32)(30,38)(31,33)(34,37)(35,40)(36,39)(1,2)(3,4)(5,7)(6,8)(9,13)(10,14)(11,18)(12,24)(15,19)(16,22)(17,23)(20,21)(25,29,31,27)(26,28,32,33)(30,35,39,37)(34,38,40,36)(1,4)(2,6)(3,7)(5,8)(9,14)(10,19)(11,22)(12,23)(13,20)(15,21)(16,17)(18,24)(25,30,31,39)(26,34,32,40)(27,35,29,37)(28,36,33,38)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.