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)(11,16)(12,17)(13,21)(14,15)(18,23)(19,20)(22,24)(25,26,30,33)(27,34,29,31)(28,36,38,32)(35,39,37,40)(1,3,6,7)(2,5,8,4)(9,10)(11,16)(12,17)(13,18)(14,15)(19,22)(20,24)(21,23)(25,27,30,29)(26,31,33,34)(28,35,38,37)(32,39,36,40)(10,15)(11,17)(18,21)(19,24)(25,28,30,38)(26,32,33,36)(27,35,29,37)(31,39,34,40)(1,4,6,5)(2,7,8,3)(9,11,14,17)(10,16,15,12)(13,19,23,24)(18,22,21,20)(25,28)(26,32)(27,35)(29,37)(30,38)(31,39)(33,36)(34,40)(1,5,6,4)(2,7,8,3)(9,12,14,16)(10,17,15,11)(13,22,23,20)(18,19,21,24)(25,29,30,27)(26,31,33,34)(28,37,38,35)(32,39,36,40)(1,2)(3,5)(4,7)(6,8)(9,13)(10,18)(11,19)(12,20)(14,23)(15,21)(16,22)(17,24)(25,26)(27,31)(28,32)(29,34)(30,33)(35,39)(36,38)(37,40) involution — undirectedA 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.