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