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