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