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