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