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