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