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