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