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