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