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