One vertex per element, one color per generator, with an edge from x to x·s.
(9,10)(11,17)(12,22)(13,19)(14,20)(15,16)(18,23)(21,24)(25,26)(27,29)(28,36)(30,34)(31,33)(32,38)(35,39)(37,40) involution — undirected(1,2,5,4)(3,6,7,8)(9,11,16,13)(10,17,15,19)(12,14,23,21)(18,24,22,20)(25,26,30,34)(27,29,33,31)(28,32,38,36)(35,37,40,39)(2,4)(3,7)(9,12,16,23)(10,18,15,22)(11,21,13,14)(17,20,19,24)(25,27,30,33)(26,31,34,29)(28,35,38,40)(32,39,36,37)(1,3,5,7)(2,6,4,8)(9,13,16,11)(10,19,15,17)(12,21,23,14)(18,20,22,24)(25,28)(26,32)(27,35)(29,37)(30,38)(31,39)(33,40)(34,36)(1,3)(2,6)(4,8)(5,7)(9,14,16,21)(10,20,15,24)(11,12,13,23)(17,22,19,18)(25,26)(27,31)(28,32)(29,33)(30,34)(35,39)(36,38)(37,40)(1,4,5,2)(3,8,7,6)(9,15,16,10)(11,19,13,17)(12,18,23,22)(14,24,21,20)(25,29,30,31)(26,33,34,27)(28,37,38,39)(32,40,36,35)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.