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