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