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