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